1. Field of the Invention
The present invention relates to an induction motor, and more particularly, to a stator of an induction motor capable of facilitating an assembly by simplifying a structure and capable of enhancing a counter electromotive force.
2. Description of the Conventional Art
Generally, an induction motor for converting electric energy into kinetic energy is used as a power source of each device and has various kinds.
FIG. 1 is a frontal section view showing one example of the induction motor, and FIG. 2 is a lateral section view showing of the induction motor. As shown, the induction motor is provided with a winding coil 210 therein and comprises: a stator 200 fixedly coupled to inside of a casing 100 of a predetermined shape; an induction rotor 300 rotatably inserted into the stator 200; a shaft 400 forcibly pressed into the induction rotor 300; and a magnet rotor 500 formed as a cylindrical shape and rotatably inserted between the stator and the induction rotor 300.
The induction rotor 300 comprises a cylindrical body 310 having a certain length, a plurality of conductor bars 320 coupled at an edge of the cylindrical body 310, end rings 330 coupled at both side surfaces of the cylindrical body 310 for connecting both ends of the conductor bars 320, and a shaft hole 340 formed at the center of the cylindrical body 310 for forcibly pressing the shaft 400.
The shaft 400 is supported at the casing 100 by a bearing 410, the magnet rotor 500 is supported at a magnet holder 510 formed as a cup shape, and the magnet holder 510 is supported at the shaft 400 by a bearing 520.
Operation of the induction motor will be explained as follows.
When an alternating current is supplied to the induction motor, an induction rotating magnet field is generated at the stator 200 on which a coil is wound, and by the induction rotating magnet field, the magnet rotor 500 is rotated. According to this, an induction rotating magnet field having an intensive magnet field is generated by the magnet rotor 500, and thereby the induction rotor 300 is rotated. As the induction rotor 300 is rotated, the shaft 400 coupled thereto is rotated thus to transmit a rotational force.
The induction motor is mainly applied to home electronics such as an air conditioner, a refrigerator, an electric fan, and etc. The home electronics has to have not only a low manufacturing cost in an aspect of price competitiveness and energy saving but also a low power consumption. To this end, a manufacturing cost of a motor which serves as a power source of the home electronics has to be lowered and efficiency thereof has to be maximized.
A component which greatly influences on the manufacturing cost and efficiency is the stator, and a structure of the stator will be explained in more detail.
FIG. 3 is a lateral section view of a stator constituting the induction motor. As shown, the stator of the induction motor comprises a stator body 220, and a winding coil 210 wound on the stator body 220. The stator body 220 includes a body portion 221 having a certain outer diameter and a length, a rotor inserting hole 222 formed in the body portion 221 for inserting the induction rotor 300, and a plurality of slots 223 formed at the body portion 221 with a certain interval and connected to the rotor inserting hole 222. One side of the slots 223 is formed as an opened shape connected to the rotor inserting hole 222, and a coil span P1, an interval between the slots 223 is constant. A protruding part between the slots 223 forms teeth 224, and stepping protrusions 225 are respectively extended at both sides of end portions of the teeth 224. End widths of the teeth 224 including the stepping protrusions 225 are the same.
The winding coil 210 is divided into two. The one is an auxiliary winding coil 211 used at the time of an initial starting of the magnet rotor 500, and the other is a main winding coil 212 used at the time of outputting of the magnet rotor 500 and the induction rotor 300 after the starting.
The main winding coil 212 divides the slots 223 according to a condition, and is inserted between the slots 223 with intervals corresponding to the number of the divided slots thus to be wound on the teeth 224. Also, the auxiliary winding coil 211 is inserted between the slots 223 with intervals corresponding to the number of the divided slots thus to be wound on the teeth 224. The main winding coil 212 is positioned outside the slots 223, and the auxiliary winding coil 211 is positioned inside the slots 223.
However, said structure is suitable for an induction motor which is not provided with the magnet rotor 500 and is inefficient for an induction motor provided with the magnet rotor 500. That is, said structure is efficient for an induction motor which is not provided with the magnet rotor 500 since the auxiliary winding coil 211 is used at the time of starting the induction rotor 300 and the main winding coil 212 is used at the time of a normal driving of the induction rotor 300 thus to have a greater output by the main winding coil 212. However, in the induction motor provided with the magnet rotor 500, the auxiliary winding coil 211 and the main winding coil 212 are used to initially start the magnet rotor 500 and to generated an output, so that said structure is inefficient. Also, coil ends of the main winding coil 212 and the auxiliary winding coil 211 are long and an winding working is complicated thus to have a high manufacturing cost.